Injection molding nozzle for manufacturing injection molded components from plastic

Abstract

The present invention refers to an injection molding nozzle for introducing a molten plastic to a mold cavity ( 15 ) of an injection molding tool via a slot gate ( 2, 2, 3 ). The injection molding nozzle includes a nozzle core ( 2, 3, 3 ) having an elongate edge ( 3 B) and is received in an opening ( 1 A, 1 ) in a housing ( 1, 1 ). A portion of the nozzle core ( 2, 3, 3 ) is spaced apart from the housing ( 1, 1 ) so as to define a nozzle flow channel that is in fluid communication between a source of the molten plastic and the slot gate ( 2, 2, 3 ), and at least a downstream portion of the nozzle flow channel that is between the housing ( 1, 1 ) and the nozzle core ( 2, 3, 3 ) surrounds the nozzle core ( 2, 3, 3 ) on all sides.

The invention claimed is: 
     
       1. An injection molding nozzle for introducing a molten plastic to a mold cavity of an injection molding tool via a slot gate, the injection molding nozzle comprising:
 a nozzle core having an elongate edge and received in an opening in a housing,
 wherein a nozzle flow channel is defined between the nozzle core and the housing, the nozzle flow channel providing fluid communication between a source of the molten plastic and the slot gate, the nozzle flow channel including
 a nozzle runner defining a downstream portion of the nozzle flow channel between the housing and the nozzle core that surrounds the nozzle core on all sides, the nozzle runner tapering in the direction of flow and being defined between an externally tapered portion of the nozzle core that tapers towards the elongate edge and an internally tapered portion of the housing that tapers towards the slot gate, 
 a manifold having an upstream inlet in fluid communication with the source of the molten plastic, the manifold having an outlet extending on opposite sides of the nozzle core in the form of first and second runner branches, the first and second runner branches being recesses within the opposite sides of the nozzle core, and each of the first and second runner branches having a cross-sectional area that reduces in a downstream direction from the upstream inlet of the manifold to respective downstream ends of the first and second runner branches, and 
 a throttle zone extending between the first and second runner branches of the manifold and the nozzle runner, by which the manifold is in fluid communication with the nozzle runner, wherein the throttle zone forms a constriction of flow of the molten plastic completely extending around the nozzle core, wherein the throttle zone has a first longitudinal length between the upstream inlet of the manifold and the nozzle runner, and a second longitudinal length between the downstream ends of the first and second runner branches of the manifold and the nozzle runner, with the first longitudinal length being different from the second longitudinal length; and 
 
 
 a heater incorporated in the nozzle core, wherein insulation is provided between the housing and the nozzle core that is configured to thermally insulate the housing against the heated nozzle core. 
 
     
     
       2. The injection molding nozzle according to  claim 1 , wherein the upstream inlet of the manifold is in fluid communication with a feeder channel of the nozzle. 
     
     
       3. The injection molding nozzle according to  claim 1 , wherein a flow resistance of the throttle zone differentiates along a length of the slot gate due to a first flow resistance created by the first longitudinal length of the throttle zone being different from a flow resistance created by the second longitudinal length of the throttle zone. 
     
     
       4. The injection molding nozzle according to  claim 1 , wherein the nozzle runner forms an inflow section connecting to the throttle zone and a downstream outflow section leading to the slot gate, the downstream outflow section having a smaller angle of inclination relative to the outflow direction of the slot gate in comparison to an angle of inclination of the inflow section relative to the outflow direction of the slot gate. 
     
     
       5. The injection molding nozzle according to  claim 1 , wherein the manifold is a first manifold with the first and second runner branches, and the nozzle further comprises a second manifold having an outlet extending on opposite sides of the nozzle core in the form of third and fourth runner branches, the third and fourth runner branches being recesses within the opposite sides of the nozzle core, and each of the third and fourth runner branches having a cross-sectional area that reduces in a downstream direction from an upstream inlet of the second manifold to respective downstream ends of the third and fourth runner branches, and wherein the first and second manifolds are symmetrical in relation to a longitudinal axis of the slot gate and together surround the nozzle core. 
     
     
       6. The injection molding nozzle according to  claim 5 , wherein the downstream ends of the first and second runner branches of the first manifold are in fluid communication with the respective downstream ends of the third and fourth runner branches of the second manifold. 
     
     
       7. The injection molding nozzle according to  claim 6 , wherein the downstream ends of the first and second runner branches of the first manifold connect to the respective downstream ends of the third and fourth runner branches of the second manifold prior to the throttle zone. 
     
     
       8. The injection molding nozzle according to  claim 5 , wherein the throttle zone further extends between the third and fourth runner branches of the second manifold and the nozzle runner, and wherein the throttle zone has the first longitudinal length between the upstream inlet of the second manifold and the nozzle runner, and the second longitudinal length between the downstream ends of the third and fourth runner branches of the second manifold and the nozzle runner. 
     
     
       9. The injection molding nozzle according to  claim 1 , wherein at least an internal boundary of the first and second runner branches of the manifold is formed by the recesses in the nozzle core. 
     
     
       10. The injection molding nozzle according to  claim 9 , wherein an external boundary of the first and second runner branches of the manifold is defined by a side wall of the opening in the housing. 
     
     
       11. The injection molding nozzle according to  claim 1 , further comprising a sleeve received in the opening in the housing and surrounding the nozzle core, and wherein an external boundary of the manifold is defined by an internal wall of the sleeve. 
     
     
       12. The injection molding nozzle according to  claim 11 , wherein the internal wall of the sleeve further defines at least a portion of an external boundary of the throttle zone. 
     
     
       13. The injection molding nozzle according to  claim 11 , wherein the sleeve is positioned between an internal shoulder of the opening in the housing and an external shoulder of the nozzle core. 
     
     
       14. The injection molding nozzle according to  claim 11 , wherein the sleeve forms a fluid seal with a body portion of the nozzle core that is upstream from the nozzle flow channel. 
     
     
       15. The injection molding nozzle according to  claim 11 , wherein the sleeve is made from a material that is more insulative than a material from which the nozzle core and/or the housing is made. 
     
     
       16. The injection molding nozzle according to  claim 1 , wherein the nozzle core and the opening in the housing are oblong, each having lengths that are greater than their widths. 
     
     
       17. The injection molding nozzle according to  claim 1 , wherein the nozzle core and the opening in the housing are cylindrical, and the nozzle core includes a pair of roof areas symmetrical in relation to a longitudinal axis of the slot gate. 
     
     
       18. The injection molding nozzle according to  claim 17 , wherein the slot gate features a plurality of branches, and the nozzle core features a plurality of pairs of roof areas corresponding to the plurality of branches, wherein the plurality of pairs of roof areas end in a plurality of edges corresponding to a shape of the slot gate. 
     
     
       19. The injection molding nozzle according to  claim 1 , wherein the housing includes a cooling channel that is aligned with a longitudinal axis of the slot gate. 
     
     
       20. The injection molding nozzle according to  claim 1 , wherein the nozzle core is movable within the housing for closing the slot gate. 
     
     
       21. The injection molding nozzle according to  claim 20 , further comprising a mold plate that defines the housing, delimits a portion of the mold cavity, and defines the slot gate leading to the mold cavity. 
     
     
       22. The injection molding nozzle according to  claim 1 , wherein the housing comprises an insert receivable in an opening in a mold plate, and wherein the insert delimits a portion of the mold cavity and defines the slot gate leading to the mold cavity. 
     
     
       23. An injection molding tool having an injection molding nozzle according to  claim 1 , wherein the injection molding tool includes a pair of mold cavities separated by a partition, and the pair of mold cavities are fed by a common injection molding nozzle, which extends on both side of the partition. 
     
     
       24. The injection molding nozzle according to  claim 1 , wherein the first longitudinal length of the throttle zone is greater than the second longitudinal length of the throttle zone. 
     
     
       25. The injection molding nozzle according to  claim 1 , wherein the first longitudinal length of the throttle zone is less than the second longitudinal length of the throttle zone.